Recovering a hijacked Google Account

My phone and wallet were stolen a few weeks back. The people who did this have been quite sophisticated and broken multiple layers of security. At this point I have been able to shore things up and put blocks to prevent further identity theft issues.

Unfortunately, they were able to hijack my Google account and change all recovery information. At this point I really don't care about the email address, but I do have tax information in Google Drive.

I have followed the instructions on the Google account recovery page and tried to do everything they suggest multiple times. At this point I wish I could at least get the account completely frozen.

Has anyone on here had success recovering a fully hijacked account?